GABA sensitivity of spectrally classified horizontal cells in goldfish retina.
We studied the GABA sensitivity of horizontal cells in the isolated goldfish retina. After the glutamatergic input to the horizontal cells was blocked with DNQX, GABA depolarized the monophasic and biphasic horizontal cells. The pharmacology of these GABA-induced depolarizations was tested with the GABA receptor antagonists bicuculline-methiodide and picrotoxin, the GABA transporter agonist nipecotic acid, and the GABA transporter antagonist SKF 89976-A. The GABA-induced responses of monophasic horizontal cells consisted of two components; one with characteristics of GABA-gated chloride channels, and one with characteristics of GABA transporters. In biphasic horizontal cells, we only found evidence for GABA-gated chloride channels. The results show that monophasic horizontal cells in goldfish contain the two components of a positive feedback loop (GABA transporters and GABA-gated chloride channels), as described in salamander. Furthermore, our results indicate that the monophasic horizontal cells may project directly to the biphasic horizontal cells, via an excitatory GABAergic pathway. We propose that the function of these GABAergic systems in horizontal cells is to abolish cone dominance in bipolar cells surround in the dark-adapted retina.
Verweij
J
J
Graduate School Neurosciences Amsterdam, Laboratory of Medical Physics, University of Amsterdam, The Netherlands.
Kamermans
M
M
Negishi
K
K
Spekreijse
H
H
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione / Q000494:pharmacology; D000818:Animals; D001640:Bicuculline / Q000031:analogs & derivatives / Q000494:pharmacology; D002352:Carrier Proteins / Q000187:drug effects / Q000378:metabolism*; D018118:Chloride Channels / Q000502:physiology; D004298:Dopamine / Q000378:metabolism / Q000494:pharmacology; D004594:Electrophysiology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D050485:GABA Plasma Membrane Transport Proteins; D006054:Goldfish; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism*; D026901:Membrane Transport Proteins; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D009557:Nipecotic Acids / Q000494:pharmacology; D027361:Organic Anion Transporters; D010852:Picrotoxin / Q000494:pharmacology; D011392:Proline / Q000031:analogs & derivatives*; D011810:Quinoxalines / Q000494:pharmacology; D018079:Receptors, GABA / Q000187:drug effects / Q000378:metabolism*; D017470:Receptors, Glutamate / Q000187:drug effects; D012160:Retina / Q000187:drug effects / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism / Q000494:pharmacology*
D018750:6-Cyano-7-nitroquinoxaline-2,3-dione; D001640:Bicuculline; D002352:Carrier Proteins; D018118:Chloride Channels; D004298:Dopamine; D018691:Excitatory Amino Acid Antagonists; D018756:GABA Antagonists; D050485:GABA Plasma Membrane Transport Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D009557:Nipecotic Acids; D027361:Organic Anion Transporters; D010852:Picrotoxin; D011392:Proline; D011810:Quinoxalines; D018079:Receptors, GABA; D017470:Receptors, Glutamate; D005680:gamma-Aminobutyric Acid; C030278:nipecotic acid; C017069:bicuculline methiodide; C056723:FG 9041; C010983:homoproline